90917820 has 144 divisors (see below), whose sum is σ = 320785920. Its totient is φ = 20412288.

The previous prime is 90917807. The next prime is 90917821. The reversal of 90917820 is 2871909.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (90917821) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 73729 + ... + 74951.

It is an arithmetic number, because the mean of its divisors is an integer number (2227680).

Almost surely, 2^90917820 is an apocalyptic number.

90917820 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 90917820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (160392960).

90917820 is an abundant number, since it is smaller than the sum of its proper divisors (229868100).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

90917820 is a wasteful number, since it uses less digits than its factorization.

90917820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1304 (or 1299 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 36.

The square root of 90917820 is about 9535.0836388571. The cubic root of 90917820 is about 449.6587041777.

The spelling of 90917820 in words is "ninety million, nine hundred seventeen thousand, eight hundred twenty".